Rui F Ribeiro
  • Member for 5 years, 7 months
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4 answers
15 votes
4k views
Why did some Spectrum games need LOAD "" CODE?
1 votes

The panoply of software titles needing LOAD "" CODE to be loaded, is centred around the early ZX Spectrum years, 1982-1984. While LOAD "" also exists in the ZX81, the technique ...

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1 answers
6 votes
407 views
Did the Timex Sinclair 2068 and the Sinclair ZX Interface 2 use totally different hardware and software techniques?
Accepted answer
10 votes

Whilst Timex assembled Sinclair ZX Spectrum computers, the Timex architecture of the TS/TC 2068 is a reengineering of the ZX Sinclair behaviour with improved and more reliable technology. In the ...

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2 answers
10 votes
814 views
Zilog Z80 estimated time discrepancy
Accepted answer
11 votes

Those two mnemonics opcodes are known to have the same timing / same inner mechanisms of mapping into HL. It is obviously a bug in documentation from the link you give us. Those two pages you mention ...

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12 answers
16 votes
7k views
How can a Z80 assembly program find out its own memory address?
7 votes

If you are in the ZX Spectrum, BC is loaded with the calling address given to USR in BASIC. So at the beginning of a C/M program it is guaranteed you know the address. Also, we do not be want/cannot ...

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2 answers
2 votes
315 views
ZX Spectrum +2 not saving
2 votes

Incorrect head alignment, dirty saving head, "dry" solder joints, oxide deposits on the head(s) over the years. Many things can have gone wrong over the years. People usually prefer opening the ...

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10 answers
63 votes
8k views
What makes accurate emulation of old systems a difficult task?
2 votes

I also wrote my own Z80/Spectrum emulators in the 90s, and have some insights to add to the already excellent answers. While much of my thinking is in line with Specktre's answer, I will add more ...

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12 answers
77 votes
18k views
Back in the late 1980s, how was commercial software for 8-bit home computers developed?
4 votes

It depends on how late into the late 80s we are talking about, and your definition of "commercial titles" By 1988-1989 got my first job developing/maintaining a C payroll package, using a Commodore ...

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6 answers
10 votes
2k views
Copying tapes "back in the day"
16 votes

In theory, it is fairly simple duplicating a tape. The problem with analog tape-to-tape copies is that sound quality lowers and spurious noises are also copied and more are generated into each new ...

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18 answers
32 votes
13k views
What were the real competitors to the early IBM PC?
-1 votes

While the IBM PC marketing was a major feat pulled out by IBM+Microsoft, the IBM PC hardware together with the DOS OS was a throwback at least 1 decade in the past for 8-bits hardware, CP/M ...

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9 answers
18 votes
14k views
Formatting a 720K floppy disk over USB fails with Windows 10
2 votes

I worked for a commercial reseller of similar machines back in the early 90s. The combination of BIOS and DOS of those machines at the time did not recognise/support formatting in 720KB, but the ...

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9 answers
17 votes
4k views
What caused the demise of BASIC/BASICA in the late 1980's?
8 votes

As BASICA only lived on ROM, to be pedantic, GW-BASIC superseded it firstly. a Básica binary implementation which was used in PC clones and eventually in all PC compatibles, IBM or not. Besides BASIC ...

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3 answers
6 votes
544 views
Origin of Dongles
6 votes

The oldest (smart) hardware "dongle" I know of is from 1985 in the ZX Spectrum 48K. To curb Internet piracy and as a "collateral side effect" also having more 16KB (e.g. 64KB for the game), Mikro-Gen ...

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6 answers
15 votes
2k views
Why did tactile-feedback keyboards lose popularity?
6 votes

Whilst the original IBM keyboards were extremely robust, they also had a bit of a clunky feel even back in the day. I actually preferred using Cherry mechanical keyboards, less noisy and slightly ...

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9 answers
47 votes
13k views
Why did the IBM PC need a sound card?
19 votes

There is another angle complementing all these answers and even the question: The original PC was mainly designed and marketed as a boring but "reliable" business machine, building on top of ...

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3 answers
6 votes
2k views
Is the SimH emulator available on macOS?
1 votes

You can also install simh from MacPorts; to install it do: port install simh As the time of this writing, MacPorts is installing simh V3.8-1. I am also adding how to run Unix System 7, as I found a ...

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2 answers
5 votes
622 views
Timex 2048 RAM contention ULA/video output
2 votes

I also found an interesting link talking about differences in the Timex inner-workings about memory/video inner workings here http://comp.sys.sinclair.narkive.com/QIaAtnsk/interrupt-timing-of-timex-...

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2 answers
9 votes
801 views
Spectrum clones 512x192 mode usable text resolution
2 votes

I had a Timex TC 2048 (compatible with the ZX Spectrum 48k) with the text extended modes, never used them much. Granted, they were not supported by the ZX Spectrum ROM in the first place and the ...

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1 answers
4 votes
390 views
CPU speedup breaking sound compatibility
3 votes

As @MichaelKjörling says "For example, you've got a perfectly good 18.2 Hz timer in any IBM PC compatible, which could easily be used to calibrate a delay loop. " It could be done indeed, any ...

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9 answers
78 votes
24k views
How were the first ZX Spectrum games written?
Accepted answer
71 votes

Interestingly enough, I stumbled in a related article, that hints firstly the (cross)development at Sinclair was made on CP/M machines, (which corroborates the Matthew Smith Manic Miner development in ...

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5 answers
21 votes
2k views
How did debugging software run without memory protection?
2 votes

A debugger may be able to defend his integrity and memory space even in arcane architectures. Granted that in the most common implementations, where you want to save speed and memory, and simplify ...

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